Surgical scanning system and process for use thereof

ABSTRACT

A surgical scanning system includes a scanner supported on a carrier movable relative to an operating room table. The carrier engages a guide that is collinear with the long axis of an operating room table. The relative movement between an operating room table and a scanner along a guide decreases the likelihood of collision therebetween. The ability to collect a scan of a patient while on an operating room table increases the likelihood of a successful surgical outcome.

RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent applicationSer. No. 09/620,161 filed Jul. 20, 2000, which claims priority of U.S.Provisional Patent Application Serial No. 60/145,349 filed Jul. 23,1999, and are incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to a surgical scanning system andmore particularly to a scanning system selectively positionable about asurgical table.

BACKGROUND OF THE INVENTION

[0003] Computerized tomography (CT) has developed as a powerfuldiagnostic tool affording a surgeon detailed imagery as to the locationof abnormal tissue intended to be incised. CT scanning is typicallyperformed as a diagnostic in response to clinical manifestations ofdisease such as neurological disorders. CT scanning is also used in thecontext of pre- and post-surgical evaluations to assess the location andsize of an abnormal tissue mass, and the success of the abnormal tissuemass incision, respectively. When post-surgical CT scanning is performedduring surgical recovery, the discovery of a residual abnormal tissuemass requires the scheduling of an additional surgical procedure. Withcurrent conventional procedures and equipment, CT scanning performedwhile a patient is still under surgical anesthesia requires thetransport of the patient to a CT scanning facility thereby compromisingsurgical field sterility and risking injury to the anesthetized patient.

[0004] As CT scanning allows for earlier diagnosis and more completeassessment as to an abnormal tissue mass, a physician is better able toassess a favorable outcome for a surgical intervention as compared toradiation or chemotherapeutic treatments. While irregularly shaped,deeply situated or multiple abnormal tissue masses were previouslylikely to be deemed inoperable, technological advances involvingposition sensing surgical aids such as catheters and roboticallycontrolled surgical instruments will increasingly allow for successfulcomplex surgical interventions. The usage of position sensing surgicalinstruments requires a reference frame within the patient's bodyrelative to the fixed components of the surgical aid. Once a frame ofreference exists, a catheter or other position sensing surgical aid isfree to navigate a preselected pathway to a desired location within thebody of a patient, thereby allowing access to body tissues which wouldotherwise not be accessible through line of sight manual surgicaltechniques.

[0005] Owing to the limitations in current applications of CT scanning,there exists a need for CT scanning to be performed while ananesthetized surgical patient lies on an operating table. Such a CTscanning system affords a surgeon instant feedback as to the success ofabnormal tissue excision and with less likelihood of surgical fieldcontamination. Further, such a system would provide a standard frame ofreference between a body tissue and position sensing surgical aids.

SUMMARY OF THE INVENTION

[0006] A surgical scanning system includes an operating room tablehaving a long axis, a scanner supported on a carrier and a guide adaptedto engage the carrier. The carrier being movable relative to theoperating room table along the guide. The long axis of the operatingroom table being collinear with the guide.

[0007] An improvement to a wheeled medical scanner including a scannermounted on a wheeled platform adapted to encompass an operating roomtable portion along a long axis of the operating room table isdisclosed. The improvement to the wheeled medical scanner includes aguide roller attached to the wheeled platform of the scanner such thatthe guide roller is adapted to engage a mechanical guide affixed to theoperating room floor collinear with the long axis of the operating roomtable.

[0008] With the ability to move a medical scanner relative to anoperating room table, a method becomes available for performing amedical scan during a surgical procedure. The process includingidentifying a scan region proximal to a long axis of an operating roomtable. Thereafter, moving a scanner along a linear guide collinear withthe long axis of the operating table so as to encompass the scan region.A scan of the scan region is then collected. The scanner is thenretracted along the guide to a location remote from the operating roomtable, thereby allowing surgical personnel access to the operatingfield.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a side view of a surgical scanning system according toone embodiment of the present invention.

[0010]FIG. 2 is a partial cutaway side view of the embodiment shown inFIG. 1 with drapes in position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] “CT gantry” as used herein refers to those structures within a CTscan ring capable of obtaining cross axial transmission information fromany of 360° of the projection across the central bore of the CT scanner.

[0012] The present invention has utility in obtaining computerizedtomography (CT) images during the conduct of a surgical procedure on apatient. The present invention directly addresses patient safety issuesby minimizing the chances of collision between a moving CT gantry, thepatient and associated surgical equipment.

[0013] CT movement is constrained herein along a predefined guidecollinear with the long axis of the CT compatible operating room (OR)table. When not active, the CT gantry is moved in a precise manner alongthe axis of the patient to the distance sufficient to allow conventionalunimpeded access to the patient by OR personnel.

[0014] The movement of the CT gantry is constrained by a mobile carrierillustratively including a platform, pallet or dolly. This mobilecarrier moves the CT gantry in a controlled fashion along a guideway. AnOR table is positioned collinear with the axis of movement of the CTgantry and carrier system. Movement of the carrier is guided by manual,mechanical, electronic, or optical systems.

[0015] The “CT compatible OR table” of the present invention ischaracterized as a patient support table which allows a patient to besafely positioned for a surgical procedure and which has structuraldesign characteristics which permit CT images to be obtained duringsurgery. The table is optionally movable. Prior to CT scanning, thetable is positioned on the floor allowing safe scanning of the patient.

[0016] Movement of a CT gantry of the present invention is constrainedalong a predefined guide collinear with the long axis of a CT compatibleOR table. The CT gantry is mounted on a mobile pallet. This pallet movesthe CT gantry and carrier system 10 in a controlled fashion along a linedictated by a guide. Preferably, the guide track is linear.

[0017] In another embodiment, a conventional wheeled pallet CT scannerdesigned to encompass an OR table portion is adapted with retractableguide rollers, the guide rollers adapted to engage a mechanical guideinstalled in the OR collinear with the long axis of an OR table. It isappreciated that the mechanical guide is installed in either a temporaryor permanent basis.

[0018] In still another embodiment, a ceiling or wall mounted track anddolly system allows a single CT scanner to be shared between a pluralityof operating rooms. The track and dolly system operating as describedherein with regard to a floor mounted guide system.

[0019] The CT compatible OR table allows a patient to be safely andproperly positioned for a cranial, spinal, or other surgical procedure.The table has design characteristics which permit CT images to beobtained during surgery.

[0020] Specialized surgical drapes and patient protection systems arealso provided with the surgical scanning system of the presentinvention.

[0021] While the present invention is detailed herein with reference toa CT scanner, it is appreciated that the present invention readilyincorporates other instruments illustratively including x-ray, magneticresonance imaging and ultrasound.

[0022] In reference to FIG. 1, a CT gantry and carrier system 10 isselectively positioned along a temporary or permanent guideway 11 whichis installed in the OR. The guideway 11 is an alignment aid used tocontrol the movement of a CT carrier 12. The guide 11 providespositional information to aid in the accurate positioning of a CTcompatible OR table 14 and of a distant alignment target device 16. Ifthe guide is mounted on the floor, it optionally also provides a surfaceto facilitate movement of the CT carrier 12 and of the OR table 14. Theguide 11 is preferably fabricated in sections to ease initial on-sitedelivery and installation. The guide surface finish or a replaceablecover thereof is compatible with standard OR requirements for cleaningpurposes.

[0023] A CT gantry 9 rests on the movable carrier 12, together making upgantry and carrier system 10. The transport of the carrier 12 moves theCT gantry 9 from its initial disengaged position, which allows normalunfettered access to a patient on the OR table 14, to the scan positionover a patient on the OR table 14. The carrier 12 engages the guide 11in a manner which assures the axis of movement of the CT 10 is collinearwith the axis of the guide 11 and, therefore, with the OR table 14. Thecarrier movement may be motorized or non-motorized.

[0024] The OR table 14 has controls to allow the patient support surfaceto be accurately leveled as well as positioned as needed for a surgicalprocedure. The OR table 14 accepts ancillary tubing and monitoring lines18. The OR table 14 optionally includes at least one articulation 20 topromote positional adjustments. A patient is safely supported beyond thefootprint of the table base 22.

[0025] The CT compatible extension 24 supports a patient while allowingradiolucent imaging in 360 degrees transverse to the long axis of the ORtable 14. The table extension 24 is fabricated from carbonfiber/graphite composite or other radiolucent materials. Optionally,embedded within the extension 24 or attached thereto are specializedmarkers of contrasting radiodensity which allow accurate positionalinformation to be encoded in CT images obtained herein. The tableextension 24 is optionally engineered to engage fittings on specializedsurgical drapes and rigid patient protection devices describedhereinbelow. Preferably, the table extension edges are engineered toengage fittings.

[0026] A distant alignment target device 16 is used in conjunction withan alignment device 26. The alignment device 26 is used in conjunctionwith a laser mounted on the OR table 14 or table extension 24. Thedevice 26 is secured to the table either directly or indirectly throughdrapes as detailed hereinbelow. Use of the target device 16 ensures thatthe axis of the OR table 14 and table extension 24 have been accuratelyaligned co-axially with the axis of the CT guide 11. It is appreciatedthat the relative positions of target device 16 and alignment device 26can be transposed. Thus positioned, collision between the CT system 10and the table extension 24 is prevented.

[0027] It is appreciated that alternate alignment configurations andmethods are operative within the present invention includingphotodetectors, acoustic sensors and referencing fixtures secured withinthe OR at locations remote from the OR table. Thus, the origin of frameof reference is arbitrary and mathematically can be transferred anywherewithin the OR.

[0028] An alignment device allows a physician to measure an anglesubtended between a medical instrument and a reference platform or an ORtable. A reference platform (not shown) is temporarily secured to asurgical patient. The reference platform is constructed of an x-rayand/or magnetic resonance compatible, temporary structural materialillustratively including plastics such as TEFLON and HDPE; low Z metalssuch as aluminum; and cartilaginous materials. The platform straddlesthe surgical site and is secured to the patient via small screws, posts,clamps or pads. The attachment points are optionally permanently mountedon the reference platform or are selectively detachable. Optionally,irregularities are incorporated into the surfaces or edges of thereference frame to form the basis of position and unique identificationinformation as is determined by medical imaging equipment.

[0029] A trajectory measurement device (not shown) is optionally securedto the reference platform during surgery. The device geometry allows itto securely engage the reference frame mounted to the patient. Thetrajectory measuring device allows the physician to pass the medicalinstrument to the entry point. As the physician holds the medicalinstrument at the entry point and later as he advances the medicalinstrument past the entry point further into the body, the trajectorymeasuring device measures two angles between the axis of the medicalinstrument and the reference frame. These two angle measurements can bepassed to a display system via electronic, optical, or other means. Thedisplay system presents the information to the physician in a clinicallymeaningful fashion. The display system may use a computer to presentmedical image information superimposed upon the trajectory information.Optionally, the system is capable of calculating the depth of theinstrument.

[0030] One method that the trajectory measuring device is used tomeasure the angle of the axis of the medical instrument would be asfollows: a planar imaging device is incorporated into each of two wallsof the central clear channel. Opposite each planar imaging device isfixed with a planar light source. The light sources and imaging devicesmay be fitted with polarizing filters to improve signal to noise ratio.As the medical instrument is passed through the central clear channel,each imaging device will detect one view of the instrument by changes inthe image. This information is passed to information processingequipment by electric, optical, magnetic, or other means. A secondmethod of measuring the angles would be achieved by substitution of theplanar arrays with multiple linear arrays of detectors and sources or bymultiple pointlike detectors and sources. Other methods to measure theangle of the medical instrument within the central clear channel wouldbe based on magnetic, electromagnetic, acoustic or mechanicalprinciples.

[0031] The system is designed to allow the trajectory measuring deviceto be placed successively on each of several reference frames which hadalready been secured to the patient. This is of importance when thepatient may require use of the system to address clinical needs such asbiopsy at each of several locations. Optionally, the trajectorymeasuring device has embedded systems which allow the device to sensewhich of the several reference frames to which it is attached. Insensing these irregularities, the system can detect secure seating ofthe trajectory measuring device on the reference frame. Optionally, thetrajectory sensing device can confirm secure seating on the referenceframes. This additional information can be passed from the referenceframe, via the properly seated trajectory device, to the informationprocessing system. This information may be used to simplify the overalluse protocols of the surgical scanning system of the present invention.

[0032] Optionally, additional patient safety is provided by aselectively retractable and/or removable shield 28, which is secured tothe table extension 24. The shield 28 serves to limit patient exposureto the CT gantry 9 in cases in which patients have some residual orunintended movement. Provision is made to ease the task of maintainingsterility during retraction and deployment of the shields.

[0033] A shield of the present invention is formed as a rigid articledesigned to protect surgical patient regions such as the head, neck, andother extremities from physical contact with a CT gantry. Further, ashield also promotes surgical field sterility when used adjacentthereto. A shield is formed to nearly any shape provided the size andshape adequately cover a desired region of a surgical patient.Illustrative shapes include a dome, bucket and cylinder. Preferably, theshield is optically transparent, else one or more optically transparentviewing windows are incorporated therein. More preferably, the shield isalso x-ray transparent. A shield according to the present invention isoptionally secured to the operating room table. Securing meansillustratively include a bow, three point fixation, dovetail clamp,interlocking grooves and the like.

[0034] A shield is used to check whether a bundled surgical patient willfit within the bore of a CT gantry. Optionally, the shield is segmentedsuch that portions thereof are removable.

[0035] To promote aseptic conditions in the operating field, specializedsurgical drapes are optionally provided which serve to maintainsterility of the surgical field as the CT gantry 9 moves over a patientas shown in FIG. 2. Drapes 30 and 32 are preferably placed on both theOR table patient volume and over CT system, respectively. Adhesive ormechanical fixturing means are integrated into the drape material tosecure the drapes 30 to the underlying OR table 14 and CT system 10.Additionally, at least one fixturing fitting is optionally integratedinto the drapes 30 to secure external medical equipment (not shown) tothe drape 30 or, indirectly, to the OR table 14 or CT gantry 10.

[0036] The surgical drape 30 is provided herein to maintain an asepticsurgical field both above and below a patient supported upon a surgicaltable. While it is appreciated that numerous configurations of drapescan be created to surround a patient above and below a supporting table,preferably a tube-type drape encompasses a patient supported on a table.Employing similar surgical drapes about medical equipment, suchequipment is safely and repeatedly placed around the surgical fieldwithout contaminating the surgical field or the medical equipment. Bothopen and closed tube drapes are operative herein.

[0037] According to one method of the present invention, a drape iscollapsed along its long axis which preferably has a fold facilitatingregular and compact disengagement, such fold illustratively including anaccordion fold. Rigid or semi-rigid structures incorporated with a drapeoperate as hand holds such that sterile gowned personnel selectivelyexpand and collapse the drape along the length of the patient.Preferably, the mechanical structures are formed as ring handles. Ringhandles optionally engage fixtures on the operating room table or areselectively removable.

[0038] An alternative method of utilizing a drape according to thepresent invention entails collapsing a drape to the edge of a surgicaltable. A drawstring or other means is optionally incorporated into thedrape to gather the drape together to more closely conform to surgicaltable and patient contours.

[0039] A fixture is optionally bonded to the exterior surface of adrape. A fixture is optionally included to engage complementary fixtureson the operating room table. A similar fixture on the internal surfaceof the drape permits complementary fixtures to be secured thereto. Thus,sterile equipment is securely fastened to the operating room tablethrough the drape without destroying the sterile integrity of themechanical drape barrier. Other types of incorporated fixturesfacilitate placement and attachment of medical equipment, tubing, wiresand the like. A drape according to the present invention is optionallyprovided with a preformed opening in the drape. The drape opening ispositioned in the vicinity of the surgical incision upon extension ofthe drape over a patient supported on an operating room table.

[0040] The specialized drape 32 is provided herein to allow a CT scandevice to be used during a sterile procedure. The drape 32 permits theCT scanner to encompass a patient without violating the sterile field.The CT drape 32 optionally incorporates several fixtures bonded to thedrape. Fixtures on the non-sterile side of the drape engagecomplementary fixtures on the CT scanner, whereas fixtures on thesterile side of the drape permit complementary fixtures to be secured tothe drape and by way of the incorporated drape fixture to the CTscanner. Thus, sterile equipment is attached to the CT through the drapewithout destroying the integrity of the sterile mechanical barrier. Itis appreciated that other types of fixtures are incorporated to one sideof the drape in order to place and secure medical equipment, tubing,wires and the like.

[0041] A similar specialized drape is adapted for imaging devices suchas a C-arm.

[0042] A subset of the control and display functions, generally shown at34, are positioned at any location within the sterile field for surgicalaccess.

[0043] To aid in calibration of the present invention, a phantom (notshown) is provided to verify performance. The phantom contains elementswhich represent Hounsfield densities typical of the central nervoussystem (CNS) and surrounding structures. Spatial, density and contrastresolution is then calibrated with the phantom positioned where thepatient torso would rest by moving the CT system 10 in a scan positionover the OR table extension 24.

[0044] Prior to each clinical case, a protocol is preferably followed,and an initialization protocol with setup and calibration phases shouldbe followed. This protocol confirms that the CT system 10 and patientsafety systems are functioning properly.

[0045] An exemplary protocol according to the present inventionincludes: If a CT guide is of the temporary configuration, it is securedat this time.

[0046] Thereafter, a CT compatible extension is secured to the end ofthe OR table. Proper placement is required in order to assure safe loadbearing of a patient's weight. Moreover, the axis of a CT compatibletable extension is essentially collinear with the axis of the remainderof the OR table in order to avoid potential collision between systemcomponents.

[0047] The CT compatible table extension includes an embedded orattached x-ray contrasting radiodensity shape to locate a scan imagerelative to a reference point. The opaque shape is constructed from avariety of conventional radio-opaque materials. The shape isalternatively a complex structure which allows identification based onthe complexity of the shape or is well defined to allow calculation of ascan slice based on mathematical calculation.

[0048] Laser alignment devices are then secured to the radiolucentextension. The devices project illuminated alignment cues onto a target.The target or preferably a plurality of targets located at preselectedintervals are positioned so as to assure a safe location of a patientwith respect to a CT gantry.

[0049] A CT calibration phantom is then placed on the OR table in aposition corresponding to the head and spine of the patient and a rigidpatient protection shield is positioned thereover.

[0050] CT scans of the phantom are then collected. Phantom scans verify:the movement control system; the CT scan mechanism; and the CT spatialand density resolution.

[0051] Thereafter, the CT gantry is returned to the disengaged position,leaving the OR table freely and widely accessible for full clinical use.

[0052] Following a calibration procedure, a patient is positioned on theOR table. Routine clinical precautions for placement and padding arefollowed. Care is taken to position the anatomic region of CT interestwithin the allowable scanning locations of the radiolucent tableextension.

[0053] Typically, physiologic monitoring lines and anesthetic airwaymanagement equipment are installed. All lines and tubing are then placedwithin the guideways of the radiolucent table extension and/or thetable.

[0054] The laser alignment devices are then secured to the radiolucenttable extension.

[0055] Reconfirmation of the proper alignment of the radiolucentextension allows for correction of any misalignment associated with thepatient's weight or from the preceding positioning steps. Thereafter, nomovement of the OR table volume encompassing the patient is performed.

[0056] The rigid patient protection shields are then secured to the ORtable. Such shields can be repositioned both before and after steriledraping. Preferably, such shields are in position prior to moving the CTgantry.

[0057] Optionally, an initial scan is obtained prior to draping. Thisscan is useful, for example, in refining the planned surgical incisionsite.

[0058] The patient is then draped, and the shields are placed in theretracted position to allow the routine aspects of the clinicalprocedure to proceed in conventional fashion.

[0059] The CT gantry is then draped. Typically, standard perioperativeprecautions are followed with regards to respecting the sterility of thedraped equipment. Draping of the CT is optionally postponed until thephysician has decided that intra-operative scanning will be performed.Thereby saving the cost of the CT drape if scanning is not going tooccur during a surgical procedure.

[0060] At the election of the operating physician, scans are performedduring the surgical procedure. Prior to each of these intra-operativescans, the rigid protection shields are repositioned in the SCANposition and the laser alignment aids are used to reconfirm alignment ofthe radiolucent table extension. The CT gantry is optionallyrepositioned in a disengaged position while not in use to facilitateaccess to the patient.

[0061] Lastly, at the election of the operating physician, a final scanis performed at the conclusion of the surgical procedure. Clinicalindications for so doing illustratively include documentation of thefinal anatomic result of the procedure. Prior to such a scan, the rigidprotection shields are repositioned in the SCAN position and the laseralignment device is used to reconfirm current alignment of theradiolucent table extension. The CT system is optionally repositioned tothe DISENGAGE position while not in use to facilitate access to thepatient.

[0062] Various modifications of the instant invention in addition tothose shown and described herein will be apparent to those skilled inthe art from the above description. Such modifications are also intendedto fall within the scope of the appended claims.

1. A surgical scanning system comprising: an operating room table havinga long axis; a scanner supported on a carrier, said carrier movablerelative to said operating room table; a guide adapted to engage saidcarrier, wherein said guide is collinear with the long axis of saidoperating room table; a stationary alignment target a measurabledistance remote from said operating room table; and an alignment deviceaffixed to said operating room table and projecting a laser beam towardssaid target.
 2. The system of claim 1 wherein said scanner is acomputerized tomography scanner.
 3. The system of claim 1 wherein saidoperating room table has an immovable table base.
 4. The system of claim1 wherein said carrier is selected from the group consisting of apallet, platform and dolly.
 5. The system of claim 1 wherein saidoperating room table engages said guide, said operating room tablemovable relative to said carrier.
 6. The system of claim 1 wherein saidoperating room table is articulated.
 7. The system of claim 1 whereinsaid operating table further comprises a radiolucent extension.
 8. Thesystem of claim 7 wherein the radiolucent extension comprises at leastone marker of a contrasting radiodensity.
 9. The system of claim 1wherein said alignment device is affixed to the radiolucent extension.10. The system of claim 1 further comprising a surgical drape adapted toengage said surgical table and a human body portion encompassing volumeabove said table.
 11. The system of claim 10 wherein said surgical drapefurther comprises at least one fixturing fitting.
 12. The system ofclaim 1 further comprising a scanner drape affixed over said scanner.13. A surgical scanning system comprising: an operating room tablehaving a long axis; a scanner supported on a carrier, said carriermovable relative to said operating room table; and a reference platformsecured to said operating room table and defining a volume over saidoperating room table.
 14. The surgical scanning system of claim 13further comprising a trajectory measurement device secured to saidreference platform wherein said trajectory measuring device measures twoangles between an axis of said scanner and said reference platform. 15.The system of claim 13 further comprising a stationary alignment targeta measurable distance remote from said operating room table and analignment device affixed to said operating room table.
 16. The system ofclaim 13 wherein said scanner is a computerized tomography scanner. 17.The system of claim 13 wherein said operating room table has animmovable table base.
 18. The system of claim 13 wherein said carrier isselected from the group consisting of a pallet, platform and dolly. 19.The system of claim 13 wherein said operating room table engages saidguide, said operating room table movable relative to said carrier. 20.The system of claim 13 wherein said operating room table is articulated.21. The system of claim 13 wherein said operating table furthercomprises a radiolucent extension.
 22. The system of claim 21 whereinthe radiolucent extension comprises at least one marker of a contrastingradiodensity.
 23. The system of claim 13 wherein said alignment deviceis affixed to the radiolucent extension.
 24. The system of claim 13further comprising a surgical drape adapted to engage said surgicaltable and a human body portion encompassing volume above said table. 25.The system of claim 24 wherein said surgical drape further comprises atleast one fixturing fitting.
 26. The system of claim 13 furthercomprising a scanner drape affixed over said scanner.